Screen Tester - Each slide will show an image that makes any dead/stuck pixels, discoloration, scratches, and dust...
Dead Pixel Locator - Locate dead pixels or lit pixels on your LCD monitor or plasma displays, TVs.
InjuredPixels - Easily check your PC, laptop, tablet, smartphone, connected screen or TV for dead pixels, scratches...
Monteon - Free online-service to test a computer monitor, laptop screen, TV or mobile device display
lcdtest - LCD monitor test pattern generator
Screentest - Program for testing the quality of CRT/LCD screens. It displays various patterns and allows you to estimate the quality of your CRT/LCD monitor.